This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section. Abbreviations that may be found in the specification and/or the drawing figures are defined below at the end of the specification but prior to the claims.
There has been recent interest in antenna systems that allow antenna beam patterns to be manipulated in the elevation dimension in addition to the azimuth dimension. For instance, a base station may choose to “point” beams “upward” toward user equipment that is near an edge of the cell. Similarly, the base station may choose to point beams downward toward user equipment that are in the middle of the cell or close to the base station. This beam pattern manipulation can provide an improvement for the user equipment within the beam and may also provide less interference for the user equipment (or small cells) not within the beam.
One technique for directing the beams is using an antenna array that provides mechanical downtilt. Another technique (which may be combined with mechanical downtilt) is by dynamically adjusting the radiation patterns of an active antenna system. In particular, in a base station equipped with an antenna array system, the radiation pattern of the antenna array system may be dynamically adjustable. This adjustment may be performed with feedback from the user equipment (UE) where the feedback is an index of a matrix or vector from a codebook containing multiple matrices or vectors. However since codebooks are pre-defined (e.g., by a standards body) the resulting beam pattern after applying the selected matrix or vector will not match the desired pattern.
Although these techniques provide certain benefits, the use of these techniques could be improved.